In recent years, an enormous amount of information (electronic data) is stored on the network, with increase in speed and reduction in cost of information processing techniques and spread of network techniques such as the Internet technique. For example, on a bulletin board (a bulletin board system) on the Internet, remarks posted by the users are collected in the chronological order.
An information recommendation technique to recommend various types of information has been proposed to enable the user to obtain desired information. Examples of the technique include a technique of generating a feature vector from a bulletin board to analyze the feature. In the technique, for example, when the user inputs a keyword, a bulletin board having a feature corresponding to the input keyword is presented to the user.